Chemical Reactions - TeacherTubecdn-media1.teachertube.com/doc601/579.pdfPurpose: To learn to differentiate among the five general types of Chemical Reactions. Safety: Wear gloves,

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Chemical Reactions Unit 8

Ah, chemical reactions: the really fun part of chemistry. Mixing things together and standing back to watch what happens. After all, we now know plenty about chemical bonds

(our previous unit)…it’s time to break some. We’ll be doing lots of that in this unit. We have three labs with plenty of opportunity to mix stuff, and

identify strange substances. Our goals are to:

1. Figure out if a chemical reaction is occurring 2. Determine what type of reaction is occurring 3. Find out exactly what is going on by writing a balanced chemical equation 4. Become skilled at performing reactions by using appropriate solvents 5. Apply our knowledge to working with some acids and bases 6. Use all of this knowledge to identify mysterious unknown substances 7. Think about how we can perform chemical reactions using exactly the right amounts of reactants-

this will be the subject of our next unit: Stoichiometry.

Tentative Schedule Day 1

Lab: lab8.1: Evidence for a chemical change Lesson: Chemical change; writing chemical reactions Homework:

ws8.1: Physical and chemical change ws8.2: Balancing chemical reactions

Day 2: Lesson: 5 types of chemical reactions Lab: lab8.2: 5 types of chemical reactions Homework:

ws8.3: predicting reaction products ws8.4: signs of a reaction/5types/balancing reactions

Day 3 Lesson: Solvents; introduction to acids and bases Lab: complete previous labs Homework:

Ws8.5 5 types of reactions Day 4

Lab: lab8.3: Identification of unknown chemicals Lesson: Review- how to ace this unit Homework: Review for unit test

Day 5 Test: Chemical Reactions

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Name:__________________________________ Period:______ lab 8.1

Evidence for a Chemical Change (10 Points)

Purpose: To observe a sequence of changes that occur when a solution of copper (II) nitrate is treated

with a series of different reactants. All the reactions occur in the same test tube. At each step you will look for evidence that a new substance is formed.

Safety: Wear gloves, goggles and aprons. Materials: - 1 Test Tube - Bunsen Burner - Ring Stand

- Aluminum Foil - 100 mL Beaker - Crucible Tongs - Ruler - Glass Stirring Rod - Wire Gauze - Evaporating Dish - Cooper (II) Nitrate - Sodium Hydroxide - 1.5 M HCl Procedure: Four reactions will take place in one test tube.

1. Perform the first reaction by adding CuNO3 and NaOH to a test tube. What signs were there of a chemical reaction?

2. Keep this first product from this reaction and heat the test tube in hot water to produce a second

product. What signs were there of a chemical reaction?

3. Keep the second product and add HCl to form a third product.

What signs were there of a chemical reaction? 4. Keep the third product and add a rolled strip of Aluminum Foil to form the final product.

What signs were there of a chemical reaction? Please clean up and have your instructor sign off:

Answer the questions on the other side of this paper at your desk.

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1. The two new substances for the first reaction are in the tube are Copper (II) Hydroxide and Sodium

Nitrate. Write a balanced chemical reaction down in the form A + B C + D. 2. The products of the second reaction are Copper (II) Oxide and Water Write a balanced chemical reaction down in the form A + B C + D. 3. The products of the third reaction are Copper (II) Chloride and Water. Write a balanced chemical reaction down in the form A + B C + D. 4. There are two reactions occurring for the fourth reaction: Copper (II) Chloride + Aluminum Copper + Aluminum Chloride Aluminum + Hydrochloric Acid Hydrogen + Aluminum Chloride Write balanced chemical reactions down in the form A + B C + D.

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Name:___________________________________ Period:______ lab 8.2

Types of Chemical Reactions (10 Points)

Purpose: To learn to differentiate among the five general types of Chemical

Reactions. Safety: Wear gloves, goggles and aprons. Materials: - 5 Test Tubes - Bunsen Burner - Dropper Pipet -

Tongs - Iron Filings - 0.1 M CuSO4 Solution - 0.1 M Fe(NO3)3 Solution - 0.1 M KI Solution - CuSO4 · 5 H2O - Mg Ribbon - 6M HCl - 3% H2O2 Procedure: Part 1: Iron Metal and Copper (II) Sulfate Solution:

1. Fill a test tube ¼ full of Copper (II) Sulfate Solution. 2. Add approximately 2 g of Iron Filings to the Solution. 3. Observe the Reaction for 5 minutes. 4. Discard the Contents and clean the test tube. 5. The two new substances are Iron (II) Sulfate and Copper.

What did you observe? ____________________________________________________ ___________________________________________________________________

How do you know a chemical change occurred? _________________________________ Write a balanced chemical equation for the reaction you performed: ___________________________________________________________________ What type of reaction was this? ______________________________________________

Part 2: Iron (III) Nitrate and Potassium Iodide Solution

1. Put 2 mL of Iron (III) nitrate solution in a test tube. 2. Add 5-10 drops of Potassium Iodide solution. 3. Observe the Reaction that has occurred. 4. Discard the contents and clean the test tube. 5. The two new substances are Iron (III) Iodide and Potassium Nitrate.

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What did you observe? ____________________________________________________ ___________________________________________________________________


Part III. Procedure for heating Copper (II) Sulfate Crystals

1. Put a few pea size crystals of Copper (II) Sulfate Pentahydrate into a test tube. 2. Fasten a utility clamp to the upper end of the test tube. 3. Hold the tube by the clamp so that it is almost parallel to the surface of the lab bench. Warning: Do not point the open end of the test tube at anyone. 4. Observe the material as you gently heat the tube in a Bunsen burner blame for 30 seconds. 5. Discard the contents and clean the test tube. 6. The new substances are Copper (II) Sulfate and Water. What did you observe? ____________________________________________________ ___________________________________________________________________


Part IV. Procedure for Magnesium Metal and Hydrochloric Acid

1. Fill one test tube ½ full of Hydrochloric Acid. 2. Place the test tube in a rack. 3. Put a small piece of Magnesium metal into the test tube. (1-2 cm in length) 4. If you observe a gas forming, test its identity by holding a burning wooden splint at the mouth of

the test tube. Warning: Do not put the splint into the solution. 5. Discard the contents and clean the test tube. 6. The two new substances in the tube are Hydrogen Gas and Magnesium Chloride. What did you observe? ____________________________________________________

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___________________________________________________________________ How do you know a chemical change occurred? _________________________________

Write a balanced chemical equation for the reaction you performed: __________________________________________________________________ What type of reaction was this? ______________________________________________

Part V: Procedure for Heating Hydrogen Peroxide

1. Add 2 mL of 3% Hydrogen Peroxide Solution to a test tube. 2. Use a utility clamp to secure the tube to the ring stand. Warning: Do not point the open end of the test tube at anyone. 3. Observe the material as you very gently heat the tube. 4. If you observe a gas forming, test for its identity by carefully holding a lit match above the

solution Warning: Do not put the match into the solution. 5. Discard the contents and clean the test tube. 6. The two new substances in the tube are Oxygen gas and Water. What did you observe? ____________________________________________________ ___________________________________________________________________


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Name_______________________ Period______ Date lab8.3

Identification of Unknown Chemicals Experiment

There are five flasks containing solutions that are unlabeled. They are:

1. Hydrochloric Acid in water: HCl (aq.) 2. Salt water: NaCl (aq.) 3. Sugar water: C6H12O6 (aq.) 4. Baking soda in water: NaHCO3 (aq.) 5. Pure Water: H2O (l).

Your job is to figure out the identity of each unknown. As always, NEVER TASTE anything in the lab. Some of these chemicals, especially hydrochloric acid, are

highly toxic. Solid and aqueous samples of each are available. Suggestions: Think about the reactivity of each substance. Is there something it will react with that will reveal it’s

identity? -You may want to mix different combinations of 2 unknowns. Only mix a few drops of each: 1 mL of each

unknown is all you get. -You may want to test the pH your unknowns and compare them to authentic samples. On the following page, indicate the identity of each unknown, and your data that supports that

conclusion.

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1. Identity of unknown #1: Explanation: 2. Identity of unknown #2: Explanation: 3. Identity of unknown #3: Explanation: 4. Identity of unknown #4: Explanation: 5. Identity of unknown #5: Explanation:

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Name________________________________Period_______________WS8.1

Physical and Chemical Change Worksheet

Imagine a new spring day. The snow is melting, birds are singing. You’re inside by a warm fire, drinking hot cocoa. Consider all these changes that are going on from a chemists perspective. What is happening? Are all of these observations examples of chemical reactions? Or are they physical processes? In a physical change the identity of the substance is retained. For example, when water boils, it is converted from liquid water to steam- but it is still water.

In a chemical change, the identity of the substance changes. For example, baking soda mixed with vinegar forms several new substances, including carbon dioxide gas. We can summarize four of the common signs of a chemical

reaction by using the acronym COOL:

Color Odor Outgassing Lower or Higher Temperature

Note that they are only signs- you may observe all of them and others as well, and it is still only a physical change. The only way to know for sure is to chemically analyze what happened. ___________________________________________________________________

1. Ice melts. What are the COOL signs of a chemical reaction you observe? Is it a chemical reaction?

2. Wood burns. What are the COOL signs of a chemical reaction you observe?

Is it a chemical reaction? 3. Iron rusts. What are the COOL signs of a chemical reaction Is it a chemical reaction?

4. Give an example of a physical change: 5. Give an example of a chemical change:

6. Describe three chemical reactions going on in your body right now: 1. 2. 3.

7. Describe a physical change and a chemical change while making s’mores (ask a friend if you don’t know what they are)

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Check whether the process is physical or chemical

observation physical chemical

You cut your hair Mixing sugar and water Making a peanut, pretzel and cereal mixture Baking soda reacts with vinegar and forms a gas A piece of metal is bent in half Methanol is burned and leaves a residue An aspirin is crushed into fine powder Copper turns green when exposed to the environment Two clear liquids are mixed and a yellow color forms Baking cookies Diamonds are used to scratch glass A tree burns to form ashes A piece of paper is crumpled up Water freezes to form ice

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Name___________________________ Period____________________ ws8.2

Balancing Chemical Equations It was discovered in 1909 that if you mix nitrogen and hydrogen under the right conditions it will form ammonia (NH3), which is useful for cleaning windows, fertilizer, and munitions. It is now known as the Haber Process. But how much of each should you use? We can find out by writing a balanced chemical equation. We start by writing a chemical equation, and place lines in front of each reactant

____ N2 + ____ H2 ____ NH3

Substances often don’t react in a 1:1 ratio. To find out the ratios, we modify the number of molecules on each side until it is balanced. Look at the reaction above. There are two nitrogen atoms as reactants, but only one for product. We fix this by placing a 2 in front of the ammonia product. But now we have only two hydrogen atoms reacting, but they are forming 6 hydrogen atoms. We solve this by placing a 3 in front of hydrogen, and it is now balanced:

1 N2 + 3 H2 2 NH3

This tells us we need a lot of hydrogen for this reaction- three molecules of hydrogen for each molecule of nitrogen. ____________________________________________________________________________ Balance the equations below:

1) ____ KClO3 ____ KCl + ____ O2

2) ____ NaCl + ____ F2 ____ NaF + ____ Cl2

3) ____ H2 + ____ O2 ____ H2O

4) ____ CH4 + ____ O2 ____ CO2 + ____ H2O

5) ____ P + ____O2 ____P2O5

6) ____ Na + ____ H2O ____ NaOH + ____H2

7) ____ Ag2O ____ Ag + ____O2

8) ____ S8 + ____O2 ____ SO3

9) ____ K + ____ MgBr ____ KBr + ____ Mg

10) ____ HCl + ____ CaCO3 ____ CaCl2 + ____H2O + ____ CO2

11) ____ HNO3 + ____ NaHCO3 ____ NaNO3 + ____ H2O + ____ CO2

12) ____ H2O + ____ O2 ____ H2O2

13) ____ NaBr + ____ CaF2 ____ NaF + ____ CaBr2

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Balancing Chemical Equations – Answer Key Balance the equations below:

1) 2 KClO3 2 KCl + 3 O2

2) 2 NaCl + 1 F2 2 NaF + 1 Cl2

3) 2 H2 + 1 O2 2 H2O

4) 1 CH4 + 2 O2 1 CO2 + 2 H2O

5) 4 P + 5 O2 2 P2O5

6) 2 Na + 2 H2O 2 NaOH + 1 H2

7) 2 Ag2O 4 Ag + 1 O2

8) 1 S8 + 12 O2 8 SO3

9) 1 K + 1 MgBr 1 KBr + 1 Mg

10) 2 HCl + 1 CaCO3 1 CaCl2 + 1 H2O + 1 CO2

11) 1 HNO3 + 1 NaHCO3 1 NaNO3 + 1 H2O + 1 CO2

12) 2 H2O + 1 O2 2 H2O2

13) 2 NaBr + 1 CaF2 2 NaF + 1 CaBr2

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Name: ____________________________________ Period: _____ ws8.3

Predicting Reaction Products

Directions: Balance the equations and predict the products for the following reactions: Hint:

Ionic compounds tend to undergo replacement.

Combustion reactions have O2 as a reactant. They usually produce CO2 and water

Lone reactants must decompose

Pure metals can combine with halogens in a synthesis reaction.

1)____ NaOH + ____ HCl

2) ____ C2H4O2 + ____ O2

3) ____ Mg + _____Cl2

4) ____ PbSO4 + ____ AgNO3

5) ____ PBr3

6) ____ HBr + ____ Fe

7) ____ KMnO4 + ____ ZnCl2

8) ____Ag + ____ Sn(OH)4

9) ____ O2 + ____ C5H12O2

10) ____ H2O2

Example: _ Na + _ FeBr3

Answer: 3 Na + 1 FeBr3 3 NaBr + Fe

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Predicting Reaction Products - Solutions

Balance the equations and predict the products for the following reactions:

1) 2 NaOH + 1 H2SO4 1 Na2SO4 + 2 H2O

2) 1 C2H4O2 + 2 O2 2 CO2 + 2 H2O

3) 1 Mg + 1 Cl2 1 MgCl2

4) 1 PbSO4 + 2 AgNO3 1 Ag2SO4 + 1 Pb(NO3)2

5) 4 PBr3 1 P4 + 6 Br2

6) 2 HBr + 1 Fe 1 H2 + 1 FeBr2 OR 6 HBr + 2 Fe 3 H2 + 2 FeBr3

7) 2 KMnO4 + 1 ZnCl2 2 KCl + 1 Zn(MnO4)2

8) 4 Ag + 1 Sn(OH)4 1 Sn + 4 AgOH

9) 7 O2 + 1 C5H12O2 5 CO2 + 6 H2O

10) 1 H2O2 1 H2 + 1 O2 OR 2 H2O2 2 H2O + 1 O2

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Name________________________Period___________ ws8.4 1. When someone smokes a cigarette, what are the signs of a chemical reaction?

Is it a chemical reaction?

What type of chemical reaction is it, if any? 2. When water boils, what are the signs of a chemical reaction?

Is it a chemical reaction? What type of chemical reaction is it, if any?

3. Balance the following chemical reactions:

a) ____ Ag2O ____ Ag + ____O2

b) ____ S8 + ____O2 ____ SO3

c) ____ K + ____ MgBr ____ KBr + ____ Mg

d) ____ H2O + ____ O2 ____ H2O2

e) ____ NaBr + ____ CaF2 ____ NaF + ____ CaBr2

4. For each reaction a- e, classify it according to which type it is: synthesis, combustion, decomposition,

single replacement, or double replacement.

a. b. c. d. e.

/ /

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Name________________________ Period____________ws 8.5

Types of Reactions Worksheet Balance the following equations and indicate the type of reaction taking place: 1) ____ NaBr + ____ H3PO4 ____ Na3PO4 + ____ HBr

Type of reaction: ____________________ Answer: 3 NaBr + 1 H3PO4 1 Na3PO4 + 3 HBr

Type of reaction: double displacement

2) ____ Ca(OH)2 + ____ Al2(SO4)3 ____ CaSO4 + ____ Al(OH)3

Type of reaction: ____________________

3) ____ Mg + ____ Fe2O3 ____ Fe + ____ MgO

Type of reaction: ____________________

4) ____ C2H4 + ____ O2 ____ CO2 + ____ H2O

Type of reaction: ____________________

5) ____ PbSO4 ____ PbSO3 + ____ O2

Type of reaction: ____________________

6) ____ NH3 + ____ I2 ____ N2I6 + ____ H2

Type of reaction: ____________________

7) ____ H2O + ____ SO3 ____ H2SO4

Type of reaction: ____________________

8) ____ H2SO4 + ____ NH4OH ____ H2O + ____ (NH4)2SO4 Type of reaction: ____________________

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Types of Reactions Worksheet – Solutions Balance the following equations and indicate the type of reaction taking place: 1) 3 NaBr + 1 H3PO4 1 Na3PO4 + 3 HBr


2) 3 Ca(OH)2 + 1 Al2(SO4)3 3 CaSO4 + 2 Al(OH)3


3) 3 Mg + 1 Fe2O3 2 Fe + 3 MgO

Type of reaction: single displacement

4) 1 C2H4 + 3 O2 2 CO2 + 2 H2O

Type of reaction: combustion

5) 2 PbSO4 2 PbSO3 + 1 O2

Type of reaction: decomposition

6) 2 NH3 + 3 I2 1 N2I6 + 3 H2


7) 1 H2O + 1 SO3 1 H2SO4

Type of reaction: decomposition

8) 1 H2SO4 + 2 NH4OH 2 H2O + 1 (NH4)2SO4

Type of reaction: acid-base

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Name________________________________ Period_________ howtoaceit8.1

How to Ace the Reactions Exam

In this our eighth unit we explored the world of chemical reactions. This is the fundamental chemistry process: mixing things together and seeing what happens. We began by looking for the 4 COOL signs of a chemical reaction. We then focused on writing balanced chemical reactions- this is probably the toughest part of the unit. Be sure to know how to write ionic compounds correctly- we can’t balance a reaction unless it is written accurately. We then performed each of the 5 types of reactions, to get a feel for each one. In many cases we are now able to predict the products of a reaction. Ionic compounds tend to undergo replacement, combustion reactions often give the same products, and decomposition reactions often form stable common substances. To wrap up this unit we looked at the advantages of using solvents for chemical reactions. We took a sneak peek at acids and bases, which are really a subset of ionic compound s. We completed the unit by looking at reactions from the point of view of what really strikes your eye: precipitates. Performing and balancing reactions shows us the ratio that substances react in, but it still doesn’t tell us how much to mass out to do these reactions properly. This is the topic of the next unit: Stoichiometry and the Mole. To ace this unit review your notes, labs, worksheets, and this how to ace it guide. 1. What are the 4 signs of a chemical Reaction?

Suggest two other possible signs of a chemical reaction. Give examples of signs of a chemical reaction that are false positives.

2. Balancing Chemical Equations

-given formulas: ___H2 + ___O2 ____H2O -given word equations: mixing hydrogen and oxygen can create water. -given starting materials only, predict the product:

Write a balanced chemical equation describing the reaction of sodium chloride and Magnesium fluoride.

-combustion. Write a balanced chemical equation for burning hexane (C6H14).

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-practice writing ionic formulas: calcium hydroxide; iron (II) sulfate, etc. Ion charts will be available, as will the periodic table with the names of each elements. You will save a great deal of time by memorizing the common ions and elements.

3. The 5 types of reactions: 4. Precipitates- what is a precipitate? 5. Why solvents are your friends: 6. Solute and solvent: 7. Acids and bases: what they are; how they react. 8. The difference between salt water and sugar water: 9. Consider the chemical reactions you experience each day. You get up. You are breathing…that’s good. Now a biochemist could spend hours explaining it, but to us chemists you are taking in oxygen, it combines with carbon, and you exhale carbon dioxide. You’re doing it right now. We can write this as a balanced chemical reaction indicating the physical states (s, l, g, or aq) of the reactants and products as:

________( ) + _______ ( ) ________ ( ). OK, next you make a cup of tea. You put the kettle on, and your gas stove lights up. Yes, you have a gas stove, which uses a big propane tank next to your house. This is the combustion of propane (C3H8), which we can write as a balanced chemical reaction:

________( ) + _______ ( ) ________ ( ) + ________( ). You drink the tea, and eat something. Your body converts this food to energy using enzymes to catalyze the reactions, and the process is complex. Time for school. You hop in the car and fire it up, and the combustion of the hexane (C6H14) takes place in your engine:

________( ) + _______ ( ) ________ ( ) + ________( ). At school everything is going fine, but then you start to feel sick, and you go see the nurse. You are diagnosed with a sour stomach, and the nurse suggests you add some milk to your tea next time. She gives you some antacid tablets (Na2CO3) which react with the excess hydrochloric acid in your stomach:

________( ) + _______ ( ) ________ ( ) + ________( ). And you feel much better. The rest of the day is yet another wonderful day of learning at Guilford High School. You confidently ace your chemical reactions test

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Chemical Reactions - TeacherTubecdn-media1.teachertube.com/doc601/579.pdfPurpose: To learn to differentiate among the five general types of Chemical Reactions. Safety: Wear gloves,